Process for liquid purification



Patented Feb. 28, 1939 PATENT OFFICE.

PROCESS FOR. LIQUID PUBIFIOA'I'IO Oliver M. Urbain and William B. Stemen, Colum- Charles H.

bill, Ohio,

Hamster, Ohio rsto Lewis,

No Drawing. Application 24, 1938.

Serial No. 192,42

6 Claims.

This invention relates to water softening and liquid purification. More specifically, it relates to the removal of cations from liquids by a process of cation or base exchange.

Processes of water softening and cation removal have been known for a number of years. Perhaps the most commonly used materials are the zeolites, or alumino-silicates, although many other compounds having base exchange properties have been prepared. Such compounds,

however, are not satisfactory for use in waters of high acidity inasmuch as they tend to break down and lose their physical structure when brought into contact with acids.

To overcome these difficulties in the softenin of waters of high acidity, efforts have recently been made to employ hydrogen permutites or carbonaceous materials having exchangeable hydrogen ions. Although such materials do ei'fect water softening and cation removal in acid solutions, their capacity for cation exchange is very limited, thus making it necessary to employ large quantities of such materials and resulting in, excessive costs for softening of waters of high hydrogen ion concentration.

Considerable difliculty has also been experienced in the regeneration of those hydrogen permutite exchange materials now employed to effect cation exchange in acid mediums. Such materials appear to be eflective only in their original form, wherein theypossess hydrogen ions, and often have little or no cation exchange capacity after attempted regeneration.

It is an object of this invention to provide processes for water softening and liquid purification employing materials which will function satisfactorily in acid mediums. It is a further object to provide materials for base exchange having a high capacity for cations. Additionally, it is an object of this invention to provide a process for cation exchange which will permit the regeneration "of the materials employed without appreciable loss.

Other objects will be apparent to those skilled in the art from the following description of the processes and materials employed.

The materials employed in the processes of the inventionare solid insoluble cyclic organic compounds containing imino radicals within the "ring structure. Additionally, one of the atoms to which the imino group is attached must possess a double bond connection with a third atom. Such compounds are characterized in that they ionizable hydrogen atoms which give exchange properties to such compounds. The

materials may contain a plurality of replaceable hydrogen atoms. The general structure of the imino component of such compounds maybe represented by the formula N-H, the free bonds of which are attached to other elements or groups in the material.

For an eflicient exchange material, it is necessary that the solubility of such compounds be less than 0.06 grams in cc. of water at 20 C. Materials of higher solubility than this, though effective, lose their eiiiciency and make necessary frequent replacements during the process of exchanging cations.

It has been found that derivatives of such compounds with cations, i. e., compounds in which the hydrogen of the imino group has been exchanged for cations, are also effective as eation exchangers. For example, a sodium imino compound having a sodium atom in place of the hydrogen atom may be utilized to efl'ect removal of calcium cations from hard water.

It has also been found that polymers of such compounds possess the same properties of cation 4 exchange.

Accordingly, the term water insoluble solid cyclic organic compounds having an imino group within the ring and adjacent thereto anatom N-H 11-0 4 l 0 3,6-dichioro-4,5-dihydroxyphthaiimide i-mercsptoanthratriazole v I R=NH+CH:NH:OH- R=N-NH:OH;+H:O

olic imino llethylhiethylammonium Water exchange ammonium salt of cyclic compound hydroxide i m i n 0 ex 7 compound 10 In the above equations, R represents the relatively inactive cyclic portions of the material which may, of course, be one or more ring struc- 1 tures with or without attached structures. It will beseenthattheacidichydrogenatomsorthe 1s Methorh for the or such comcations of the above exchange materials will pounds are commonly known since such mateexchange positions with the cations contained rialsarcnotncwoompounds. Theirpropertyo! inthewaterbeingtreated. Theexchangedcaexchanging cations. however. has never before tions form coordinated derivatives with the imino been known so in as applicants have been able compounds. It is believed that the primary re- .0 to discover. action is a cation exchange reaction although To illustrate the method of preparation 0! one it is possible that some sorption also takes place. or the above compounds. there'is given the equa- As exemplary of the removal of calcium cations tion tor the preparation 0! 8,9-dichloronaphtho from a hard water. there s s v n t f llmving triasole: g equation showing the reaction of 8,9-dichloro- 86 01 mi-cooim-naioi Ci N-H+OHs-C0OH 2-acstamldo-l-aminc-7,8- Nltrousaeid ae-dichloronsphtho Aoetlcacid dichlaoaaphthsieno triuolo Other insoluble cyclic imino compounds having naphthotriasole with calcium chloride: the defined characteristics may be prepared by 0| c1 N= conventional organic reactions, as will be apparl L Bill; to 1511086 skilled in the art. 7 90 H.344); +3591 As has been previously mentioned, polymers of the above compounds may be utilised to eflect cation exchange. It has been found that polymerization of such exchange compounds reduces aw h m m h pfld lci m alt 1m- Hydr their solubility and thereby enhances their value W g'g'gfi 2'53 2 ;139: 3 by 2 h fg isig' g gg After the exchange materials have become exhydroxy groups to any of the compounds falling m they may be regenerated by man! with within the class above defined, and proceeding in mluflons 0f acids, bases- A Preferred conventional mermuon methods process of regeneration involves the treating of so employed in or wrifl a mumbling from to of mineral tion in conventional methods. They may be utiregenerating mluflonm be flowed through n in m mm and mm to use m the the exchange material in the conventional rem p of m softening equipment, or gmeration process, or the exhausted exchange t my be aided to the a with material may be treated with the regenerating agitation, aiter which the converted exchange 11111114111 containerscompound; are ma removed from th The regeneration Of 0118 Of the above described treated water or Med m m cyclic imino compounds which has been used to Reaction, 1mm n We compound remove calcium ions from water may be illus- '0 having an imino group within the ring and admted'by the "M011: iacent thereto an atom which is double bonded 01 N==N O1 N=N to a third atom, with hardness forming cations IL or with organic cations which one may be desirous HE-{OH 1.1414450! of removing from a soluflon, are given in the 101- a lowing equations. For purposes of illustration, the exchange materials are shown as containing M x H a only one active group, but it should be understood 1 that such materials may contain a plurality of -W 33 m such v i active group The cations removed from the water treated 2R= +0aCh (R=N)ICI+ZHCI will, of course, be found in the regenerating soluggggggg, mg H g' tion, and, iirecovery is desired, they can be repound oxohangecomacid moved by conventional methods, such as fraction- W al distillation or fractional crystallization.-

arseem vSodium salt of En um Magnesium salt sodium a clieimino cs nabs otacycliccarbonate comimino exchange compound aue pvo It is to be expressly understood that the foregoing description and examples are merely illustrative and are not to be considered as limiting this invention beyond the scope of the subioined claims.

Having thus described our invention, we claim:

1. A'process of liquid purification which comprises exchanging cations by contacting the liquid with a. water insoluble solid cyclic organic compound having an imino group within the ring and adjacent thereto an atom which is double bonded to a third atom.

2. A process of water purification which comprises removing hardness-i'orming cations by contacting the water with a water insoluble solid cyclic organic compound having an imino group within the ring and adjacent thereto an atom which is double bonded to a third atom.

3. A process for exchanging cations in liquids of high acidity which comprises contacting the liquid with a water insoluble solid cyclic organic compound having an imino group within the ring and adjacent thereto an atom which is double bonded to a third atom, characterized in that it is stable in acid solutions, possesses high exchange capacity, and is capable of being regenerated without appreciable loss.

4. A process for exchanging cations in liquids which comprises the steps of adding to the liquid 8. water insoluble solid cyclic organic compound having an iminogroup within the ring and adjacent thereto an atom which is double bonded to a third atom, agitating for a short period, and effecting removal of the converted exchange material.

5. A process for exchanging cations in liquids which comprises the step of passing the liquid through a filter charged with a water insoluble solid cyclic organic compound having an imino group within the ring and adjacent thereto an atom which is double bonded to a third atom.

6. A process for exchanging cations in liquids which comprises the steps of passing the liquid through a filter charged with a water insoluble solid cyclic organic compound having an imino group within the ring and adjacent thereto an atom which is double bonded to a third atom, and regenerating the exchange material by treatment with solutions containing exchangeable cations.

ouvna M. URBAIN. wnum a. s-rnmnm 

